Double check unloading valve



Mr'ch 5, 1946. a A. RQKWE|Ll 9 f 1 2,395,941 y l DOUBLE CHECK UNLoADNGVALVE Filed Dec. k24,` 194s ffm f vengar? means for insuring positiveoperation prior valves 'i or less of as'chematic character for thepurpose either do notrespond, .or when operation of theA of f disclosingtypical or preferred `forms of `the .ducing a conditionl commonly knownas "chaty diierent views.

vfriction producing sealsand which has positively reduced neck 1 thatisprovided. withV a radial improved pressure regulating valvearrangement 30 internally threaded to receive thev iiuid return d areas.of said valves that it requires arpredeteh theV latter is unseated.This check valve I4 is `PatentedMains,19-16L v e Y n u n .Y

UNITED STATES .PATENT OFFICE 1 Edward A. Rockwell, Cleveland,.0 hio,assignor to Pesco Products Co., Cleveland, Ohio, a corf poration of Ohioy A l Applicaticnnecemher a4, 1943; seiial-Nasiasos sclaims. (el,iwi-'15m t u vv The present invention relates to pressure reguskilled inthe art after the Vconstruction and 'lating valve arrangements and moreparticularly operation of this double check unloader valve is" to thetypel known as unloading valves adapted to understood from the withindescription.

be 'interposed between a constantly operating Y vIt is preferred toaccomplish the numerous ob pump and an accumulating system formaintainiljects and to practice this invention substantially ingpressures therein between selected limits. as hereinafter fullydescribed and asmore par- It is anv object of this invention to simplifythe ticular pointed out in the appended claims, refconstruction of anunloading valve suchIas conE erences being made to the accompanyingdraw'-V templated herein, and to'improve thel eiliciency ingA thatformsla party of this'` specification, and operation of such valve. 10wherein: v Y 4 One of the principal diiculties with regulating Fig. 1 isa sectional view taken axially through valve arrangements of theso-called unloading a doublevcheckunloader'valve arrangement illustypehas been a lack of sharp` or sensitive retrating one embodiment of vmyinvention; and

sponse to the occurrence of the maximum and Fig. Zvis a view similar toFig; 1 showing an minimum values of pressure for which the same 15.alternative embodiment "of my invention. is set to operate. Due tofriction and lackof Thedrawingis to be understood as being more reliefvalve portion is initiated the same merely improvementscontemplatedherein, and in said partially opens and vacillates in an undecided y20drawing the sameV reference charactersidentify manner between open andclosedpositions pro- `like parts whereverthese parts appear in thetering.

It is an object of this invention to provide an ing,.t is structureembodiesanelongate housing unloading valve arrangement thatr is freefrom consisting of cylinders` 5 and 6 `connected by a acting means foreiectirig the complete moveinlet stub 8,'and alongside thisv neck thereis a.v ment thereof once the same has been initiated. radial outletkstub 9,7that projects in a. direction f It is a more particular objectlto'provide an opposite theJinlet stub 1. The outletstub 9 isincorporating a pair of valves which are in effect pipe I-Il, and theinlet stub isV internally threaded connected to reciprocatetogether intoand out of for mounting a coupling I I that is connected toengagement'with their respectiveseats alternately the vfeed 'pipe I2leading from' a continuously and forming a double checkvalve assembly,011e operating pump (not shown). of said valves cooperating with a rstvalve seat A lateral port I3 in the neck portion 1 at the 01 pOl fOI-Controlling the delvelyf pressure f bottom of the inlet stub 8 providescommunication uid t0 a lSt pressure 2011 l'ehCh m5111157, hf with theinterior of the housing, and thg passage example, be an eccumuative Sysm in W ic i of fluid through said port is controlled y a. cne-` isdesired to maintain presslre betWeItlhSeleled 40 Way, outwardpressurecheck valve I 4 .thtat permaxiinum and minimum va ues, an e o er mii-,Sthe pressurevuid from 'the pump pass valve cooperating with a secondvalve seat or thr'oughgthe inlet pori-J3 .butprevents'arreverse port forcontrolling alternately the delivery to a ow. of the fluid madirectionjtowardthe pump. second pressure zone which may, for example,be The; upper portion |50f Valve 4 is. conical in for relieving the pumpto the Il'tmg line We- 45 shape and is' adapted to contact a seat I6 atthe the selected maximum pressure as een reac e Y vmmfterminal f thecop'lig "if Valve body ggteilyering pressure to another pomt 0fv Mscuphaped vand*.iclm's pas'sgewaysm", It is a further object to soarrange the effective *permlttmg ow of the mnd past the Valve' whenl:mined greater ressure to open the .reliefcontrol urge@ toward 115sSeatiby a' C911 vSPIm '8 that K valve than to mraintain the pressuredelivery valve has lts 10We1' .end .Testmg 1111011l 11h@ Wall 0f thevclosed whereby to provide a predetermined diff DeCk 7 around'tl'leInlet P01`, |3- L The DTFSSUI? 0f iet'ential in the operating pressures.e theluid opens this,l valve against the spring;y pres- ',Aazlditiorialobjects, aims and advantages of the sure and permits `vflowonthefluidthroughfthe present invention will be apparent to persons portI3 and into the hous1ng,"and-saidvalve will 'latter for f a reciprocalvalve stem relatively wide splines valve 25 was opened, the exact closeimmediately there is a tendency of the fluid to reverse its direction ofilow. Y Y At the inner end of housing member 5 there is-a valve seatlaarranged to communicate with an accumulating system conduit 35. At theinner end of housing member there is another valve seat 20 arranged tocommunicate with the return through conduit I0 for effecting theunloading of the pump. The former seat I9 preferably has a -larger areathan the an important purpose toV be described. 'I of the housing thereis 2| Vthat is provided with 22 Vand 23 that providev guiding means forlongitudinal reciprocal movement in the neck 1 and alsol to permit thepressure iluid to ilow therepast.

A chamfered check valve 24 is disposed on one terminal of stem 2| forcooperation with the valve seat I9 while the other terminal of stem. 2|carries a relief return valve 25 for alternate cooperation with valveseat 20. The outer face of relief return valve 25 is provided with anannular ange 20 and a central boss 21 extending axially therefrom toreceive coil spring 28. If desired, asecond spiral spring 20a may alsobe employed, as shown in Fig. i

Operating in the neck for effecting a refined adjustment of springloading. A follower 29 engages the outer end of spring crease ordiminish the loading thereof by means of a bolt 3|. The function ofthesesprings is to urge the relief valve 25 inwardly in the seatingdirection thereof with a selectedA force. This force is made suilicientto overcome pressures on 35 the inner face of valve 25 up to theselected maximum delivery Aressure. When the delivery pressureexceedsgte selected value for which .thel

springs are set,\suchk pressure will unseat relief outlet stub 3 to thereturn pipe I0. As'valve is opened valve 24 is moved toward closedposition, since the two valves are connected together against relativemovement. It will be noted that as this Vmovement of valve 24 takesplace mask- Ving piston-like surface 24a moves intocooperation withmasking cylinder-like surface |9a reducing or throttling vthe flowbetween valve 24 Vand seat I9. The opening `of valve 25 thus produces amomentaryv pressure withinneck por tion l below that on the accumulatorside of valve 24 with the result `that the diilerential pressure actingon the accumulator side of valve 24 becomes effective to move the samecompletely A into engagement with seat I9. Since the crosssectional areaof valve seat i9 is made greater than-that of valve seat 20 valve 24will remain closed until the pressure on the accumulator side of valve24 drops to a value below that at which determined by these relativeareas. The lower value of the pressureat which valve 25 will close will,of course, he determined by the loading adjustment of springs 28 and28a. For example, the areas may be readily given a relative size such asto cause operation in response Yto a differential of 100 lbs. per squareinch, cutting the pump in at 9,00 lbs. per v`square inch and unloadingthe same at 1,000 lhs. per square inch.

Turning to the modified form of Y structure shown in Fig. 2, 'thepressure delivery check valve |24 is provided with a hollowcylindricalpiston |34 that isgiven a suiiiciently loose t in the boreolftubular housing member to permit a lim- (not shown) through 6` thesurrounding wall. This eliminates any friction that would result from aseal. At its outer end the piston |34 normally abuts the inner end offlanged coupling |35 threaded into the outer end of a housing member |05and is connected with the pipe |36 leadinghto the accumulator (notshown). y

A cylindrical hollow throat |38, having lateral apertures |39, connectsthe transverse piston wall 31 to pressure delivery check valve |24, andsaid l apertures permit ilow of iluid into the interior of the throat|38. Within piston |34 there is a disc-shaped auxiliary check valve thatseats on an annular ange |4| surrounding the' opening into the throat|38 and said valve |40 is urged toward its seat -bye coil spring |42that is mounted in an open cage or retainer in the form of'mtalstrips|43 having lateral ends |44 that are snapped into an annular groove |45in the cylindrical wall ofthe piston |34. The auxiliary check valve |40has-serrations or splines |46 upon its peripheral edge eiective to guidethe same and when unseated permit ow of fluid the adjacentdnner end of25l 20a and. isadapted to be adjusted to in- 30V past the valveto theaccumulator.

A slightly different shaped relief returnvalve |25 is shown and aslightly modied threaled adjusting assembly is shown including a singlespring |23, an engaging piston |29, seal |30, closure plug |32 andlocknut |33. Valve seat |20 is provided with a cylinder-like maskingsurface |20a cooperating with piston-like masking surface |25a to'further insure positive operation as will appear. The stern assembly|2| for correlating the `alternating reciprocal movement of valves |24and |25, is shown as being composed of two parts, |2|a and |2|b with theinner terminals in abutting contact. These terminals are normallymaintained in this connected or abutting relation by a followup coilcompression return valve 25 to permit'the uid to flow throughI 40 springl2 IC acting in opposition to stronger spring |28 for the purposeofcausing valve |24 i to lfollow valve |25,- and this constructionhavdiierential being ing the advantage among others of facilitatingassembly. It will be apparent that in certain installations, vit may bedesirable to fasten valves |24 and |25 together and eliminate spring|2|C in a manner the equivalent of that shown in Turning now to theoperation of the modled arrangement shown in Fig. 2, it will 4be notedthat the piston |34 and associated auxiliary check valve |40 form theprincipal distinction over the modiiicationV of Fig. 1, functioning toinsure complete movement once the same has been initiated. With theparts in the position shown, pressure is being delivered through inlet|2 past check valve |4, pressure delivery check valve |24, auxiliarycheck valve |40 and outlet |36 to the accumulator. This condition of theparts will continue to prevail until the pressure delivered rises to 'apredetermined maximum value for which spring |28 is set, which-.forexample, may be 1,000 lbs. per square inch, whereupon the pressureacting on the face ofrelief return valve |25 becomes eiective to movevalve |25 against spring |28. When. valve |25 is unseated and maskingsurfacesY |20a and |25a are moved out of opposed relation there occurs aresulting mo `spaced apart relation, lsaid valves less'is still smallenough to maintain piston |34 effective to positively move the valveassemblyto the right in Fig. 2 against the action of spring |28, movingrelief return valve |25 completely free of its seat and moving pressuredelivery "valve |24 into engagement with its seat ||9. While there is asmall metered ow around piston |34 during the transitionperiod while thevalves are being operated, it is quite important that this ow becompletely shut oli thereafter. Otherwise, the accumulated pressurewould be `lissipated thereby and the pump again cut in Y prematurely. I

This unloaded condition with valve |25 in open position will continueuntil the pressure on the accumulator side of valve |24 falls to a Valueinsucient to hold valve |24 in engagement with its seat I |`9 againstthe force of spring |28 whereupon relief return valve |25v is movedtoward its seat again effecting loading of the pump and delivery to theaccumulator.

i It will be understood that while I have described my invention asapplied specifically to the problem of maintaining a range of pressuresin an accumulating system and intermittently unloading the pressuregenerator, the same has broad application to the solution of equivalentproblems. 1 For example, one check valve may lead to a first pressurefluid consumer while the other may lead to a second pressure fluidconsumer and arranged in such a manner that the first pressure fluidconsumer will be supplied With pressure up to a certain value, upon theoccurrence of which, delivery will be auto-k maticallyswitched to thesecond consumer. In the event that the two consuming devices are to beof the pulsating type, it may be desirable to eliminate the return checkvalve in order to provide fon reverse flow in the on direction.

While this invention has been described in detail in its presentpreferred form or embodiment,

it will be apparent to persons skilled-in the art;

after understanding the improvements, that various changes andmodications may be made therein without departing from the spirit orscope thereof. It is aimed in the appended claimsr to cover al1 suchchanges and modifications.

I claim:

1. In an unloading valve arrangement including a housing having an inletport, a normal ow outlet, and a relief return port, a. one-way checkvalve controlling said inlet port, axially.r spaced valve seats in saidhousing at opposite sides of said inlet port, a double check valveassembly cooperating with said seats comprising a pairof valves, meansfor maintaining said valves in being alternately engageable with saidseats; one of said valves controlling liow through said relief returnport and the other of said valves controlling flow through said normalnow outlet port. a piston connected to said normal ow valve and locatedin the flowpath therefrom, means defining a cylindrical bore receivingsaid piston and providing for limited flow between said bore and saidpiston, a valve-controlled passage through 5 said piston effecting abarto reverse flow through said piston, and spring means urging saidspindle in a direction to seat said relief return valve and to unseatsaid pressure delivery valve.

lo' 2. In an unloading valvearrangement including a4 housing having aninlet port, a check valve controlling said inlet port, a pressuredelivery valve-controlled outlet port, said inlet and outlet portsadapted to effecting a normal continuous flow of fiuid from a pump to anaccumulator, a

an area greater than that of said pressure de-.

livery valve, an ,auxiliary check valve controlled passage through saidpiston adapted to be closed upon decrease of pressure of fluid flowingthrough said housing to the accumulator, a relief return outlet valve inv-said housing, spindle spacing means interposed between said reliefreturn valve and said pressure delivery valve, said spindle meanseffecting simultaneous operation of the respective valves to close theone when the other is opened, and adjustable elastic means urging saidspindle means in a direction to open said lator, said elastic meansbeing loaded to overcome a predetermined pressure of the flowing,

return valve in a central inlet and two opposed outlets, flankingv` saidinlet valve seats on opposite sides of said inlet communicating withsaid respective outlets.

o a double check` valve assembly including opposed valvesalternately-'engageable with said respective seats, an adjustable coilcompression spring assembly urging said valve assembly in onedi rectionto seat a first one of said valves and open the other to cause deliveryof pressure fiuid to a first pressure zone or consumer, the deliv- Cil "ery of a predetermined value of pressure ,to said first zone or consumerbeing efiective to open said other valve againstthe action of saidspring f for delivering pressure fluid to a second zone or v consumeryand effective to close said first valve, the valve seat delivering tosaid lirst pressure zone or consumer` having a larger area than that oi'said other 4valve seat whereby upon closure of e the associated valve inresponse to the occurrence of said selected pressure the same is heldclosed by the pressure fromsaidiirst zone or consumer until the'same hasdropped to a predetermined differential of pressure below that whichVwas effective to close the same, and' means defining l a, piston andcylinder in communication with the discharge side of said first valve,said piston having a loose fit within said cylinder and being of alarger area than said valve seat delivering to said first zone, andanauxiliary check valve car- .ried by said piston, the opening of saidsecondr `named valve being effective to drop the pressure l differentialacross said piston and auxiliary check valve, rendering said piston inturn effective by virtue of the increased relative area thereof to causepositive movement of said first named valve into engagementwith itsseat.

t EDWARD A.' ROCKWELL.

piston on the valve of said outlet port having a pressuredelivery valvefor flow to theaccumu- Y

